The expression of CYP3A4 and of another GH responsive hepatic enzyme, CYP1A2, and CYP3A4 mRNA will be directly measured in duodenal tissue that will be obtained through endoscopic biopsies after each treatment regimen. The effect of GH pulse pattern on lipoprotein expression and bone metabolism will also be assessed by measuring serum cholesterol and apoproteins and serum and urine markers for bone formation and resorption.